Allentown Dolomite (Lower Ordovician and Upper Cambrian)
Allentown Dolomite (Wherry, 1909) - Very thin to very thick bedded dolomite containing minor orthoquartzite and shale. Upper part is medium-light- to medium-dark-gray, fine- to medium-grained, locally coarse-grained, medium- to very thick bedded dolomite. Floating quartz sand grains and two sequences of medium-light- to very light gray, thin-bedded quartzite and discontinuous, dark-gray chert lenses occur directly below upper contact. Rhythmically bedded lower dolomite beds alternate between light and dark gray weathering, medium and very light gray, fine and medium grained, and thin and medium bedded, which are interbedded with shaly dolomite. Ripple marks, crossbeds, edgewise conglomerate, mud cracks, oolites, and algal stromatolites occur throughout unit, but more typically in lower part. Shaly dolomite increases downward toward lower conformable contact with the Leithsville Formation. Oldest beds contain trilobite fauna of early Late Cambrian age; younger beds contain latest Cambrian fauna (Howell, 1945; Howell and others, 1950). Thickness about 580 m (1,900 ft).
Beekmantown Group, Lower Part (Lower Ordovician)
Beekmantown Group, Lower Part (Clarke and Schuchert, 1899) - Very thin to thick-bedded, interbedded dolomite and minor limestone. Upper beds are light-olive-gray to dark-gray, fine- to medium-grained, thin- to thick-bedded dolomite. Middle part is olivegray-, light-brown-, or dark-yellowish-orange- weathering, dark-gray, aphanitic to fine-grained, laminated to medium-bedded dolomite and light-gray to light-bluish-gray-weathering, medium-dark- to dark-gray, fine-grained, thin- to medium-bedded limestone, that is characterized by mottling with reticulate dolomite and light-olive-gray to grayish-orange, dolomitic shale laminae surrounding limestone lenses. Limestone grades laterally and down section into medium- gray, fine-grained dolomite. Lower beds consist of medium-light- to dark-gray, aphanitic to coarse-grained, laminated to medium-bedded, locally slightly fetid dolomite having thin black chert beds, quartz-sand laminae, and oolites. Lenses of light-gray, very coarse to coarse-grained dolomite and floating quartz sand grains and quartz-sand stringers at base of sequence. Lower contact placed at top of distinctive medium-gray quartzite. Contains conodonts of Cordylodus proavus to Rossodus manitouensis zones of North American Midcontinent province as used by Sweet and Bergstrom (1986). Unit Obl forms Stonehenge Formation of Drake and Lyttle (1985) and Drake and others (1985), upper and middle beds are included in Epler Formation, and lower beds are in Rickenbach Dolomite of Markewicz and Dalton (1977). Unit is about 183 m (600 ft) thick.
Buttermilk Falls Limestone and Onondaga Limestones, undivided (Middle Devonian)
Buttermilk Falls Limestone and Onondaga Limestones, undivided - Buttermilk Falls Limestone in southwestern part of outcrop belt grades into Onondaga Limestone along strike to northeast. The transition occurs north of Millville. Buttermilk Falls Limestone (Middle Devonian) (Willard, 1938) - Light- to medium-light-gray-weathering, medium- to dark-gray, thin- to medium-bedded, fossiliferous, flaggy, clayey to silty limestone and nodular black chert. Lower contact grades downward through several meters (feet) of silty limestone to interbedded limestone and calcareous siltstone of the Schoharie Formation. Thickness is approximately 82 m (270 ft). Onondaga Limestone (Middle Devonian) (Vanuxem 1840) - Light-medium-gray- weathering, medium gray, fine-grained, thin- to thick-bedded fossiliferous limestone. Black chert more abundant in upper half of unit. Lower contact grades into interbedded limestone and calcareous siltstone of the Schoharie Formation. Thickness approximately 60 m (200ft).
Coeymans Formation, Kalkberg Limestone, Coeymans Limestone, Manlius Limestone, undivided (Lower Devonian)
Coeymans Formation, Kalkberg Limestone, Coeymans Limestone, Manlius Limestone, undivided - At New York border consists of fine-grained, chert-bearing, argillaceous limestone (Kalkberg Limestone) grading downward through coarse-grained limestone (Coeymans Limestone) into fine-grained limestone (Manlius Limestone). Toward southwest these units grade into fine- to coarse-grained limestone with a marked increase in quartz sand that comprises the Coeymans Formation (Epstein and others, 1967). Total thickness 27 m (90 ft). Coeymans Formation (Epstein and others, 1967) - Medium-light-gray, fine- to coarse-grained calcareous sandstone and medium-gray, fine- to coarse-grained, medium- to thick-bedded, locally irregularly-bedded, argillaceous to arenaceous limestone containing lenses of quartz sand and nodules of black chert. Grades downward into medium-gray, fine-grained, argillaceous and arenaceous limestone containing local beds of fine- to coarse-grained pebbly calcareous sandstone. Local bioherms consisting of light-gray to light-pinkish-gray, coarse-grained to very coarse biogenic limestone are unbedded and have sharp boundaries. Lower contact of unit abrupt. Formation thickness varies from 11 m (35 ft) in northeast to 24 m (80 ft) in southwest. Kalkberg Limestone (Chadwick, 1908) - Medium-gray-weathering, medium-dark-gray, fine-grained, very thin to massively bedded fossiliferous limestone. Grades downward into fine- to medium-grained, thin-bedded, fossiliferous argillaceous limestone containing nodules and lenses of dark-gray chert. Grades to the southwest into calcareous and arenaceous rocks of the upper part of the Coeymans Formation near Wallpack Center. Lower contact placed at base of lowest black chert. Approximately 12 m (40 ft) thick. Coeymans Limestone (Clarke and Schuchert, 1899) - Medium-gray weathering, medium-dark-gray, fine-to-coarse-grained, medium- to massively bedded fossiliferous limestone and local argillaceous limestone lenses. Unit is approximately 9 m (30 ft) thick. Between Duttonville and Millville, grades into biohermal and nonbiohermal facies of medium- to coarse-grained limestone of Coeymans Formation of Epstein and others (1967). Manlius Limestone (Vanuxem, 1840) - Medium-gray weathering, medium-dark- to dark-gray, very fine to fine-grained, unevenly bedded fossiliferous limestone. Some local medium-grained limestone, yellowish-gray shale partings and biostromes. Near Hainesville, unit grades into lower part of Coeymans Formation. Lower contact abrupt and placed at top of uppermost very fine grained argillaceous limestone. Thickness approximately 11 m (35 ft).
Green Pond Conglomerate (Lower (?) and Middle Silurian)
Green Pond Conglomerate (Rogers, 1836) - Medium- to coarse-grained quartz-pebble conglomerate, quartzitic arkose and orthoquartzite, and thin- to thick-bedded reddish-brown siltstone. Grades downward into gray, very dark-red, or grayish-purple, medium- to coarse-grained, thin- to very thick bedded pebble to cobble conglomerate containing clasts of red shale, siltstone, and chert; yellowish-gray sandstone and chert; dark-gray shale and chert; and white-gray and pink milky quartz. Quartz cobbles are as long as 10 cm (4 in.), and rare red shale clasts as much as 46 cm (18 in.) across. Milky quartz pebbles average 2.5 cm (1 in.) in length. Red arkosic quartz-pebble conglomerate and quartzite are more abundant than gray and grayish-green quartzite. Unconformably overlies Martinsburg Formation, Allentown Dolomite, Leithsville Formation, or Proterozoic rocks. About 305 m (1000 ft) thick.
Jacksonburg Limestone and Sequence at Wantage, undivided (Middle Ordovician)
Jacksonburg Limestone and Sequence at Wantage, undivided - Jacksonburg Limestone - Upper part is medium- to dark-gray, laminated to thin-bedded shaly limestone and less abundant medium-gray arenaceous limestone containing quartz-sand lenses. Upper part thin to absent to northeast. Lower part is interbedded medium- to dark-gray, fine- to medium-grained, very thin to medium-bedded fossiliferous limestone and minor medium- to thick-bedded dolomite-cobble conglomerate having a limestone matrix. Unconformable on Beekmantown Group and conformable on the discontinuous sequence at Wantage in the Paulins Kill area. Contains conodonts of North American midcontinent province from Phragmodus undatus to Aphelognathus shatzeri zones of Sweet and Bergstrom (1986). Thickness ranges from 41 to 244m (135-800 ft). Sequence at Wantage - Restricted, discontinuous sequence of interbedded limestone, dolomite, conglomerate, siltstone, and shale. Upper part is medium-yellowish-brown- to olive-gray-weathering, medium- to dark-gray, very fine to fine-grained, laminated to massive limestone and dolomite that grade down into underlying clastic rocks of lower part. Upper part locally absent. Lower part ranges from grayish-red, medium-gray, pale-brown, and greenish-gray to pale-green mudstone and siltstone containing disseminated subangular to subrounded chert-gravel, quartz-sand lenses, and chert-pebble conglomerate. Lower contact unconformable. Thickness ranges from 0 to 46 m (0-150 ft).
Minisink Limestone and New Scotland Formation, undivided (Lower Devonian)
Minisink Limestone and New Scotland Formation, undivided - Minisink Limestone (Epstein and others, 1967) - Light-medium-gray-weathering, medium-gray, fine-grained, medium-bedded, partly massive, argillaceous fossiliferous limestone. Some nodules and lenses of purer limestone occur locally. Lower contact gradational. Thickness uniformly 7 m (23 ft). New Scotland Formation (Clarke and Schuchert, 1899) - Upper part is dark-gray, very fine grained, laminated to thin-bedded siliceous shale containing pods of medium-dark-gray, very fine grained limestone; scattered thin beds and lenses of medium-gray, fine-grained argillaceous fossiliferous limestone; and small dark-gray chert nodules. Lower part is medium-dark-gray, thin-bedded, siliceous, fossiliferous calcareous shale. Contains thin beds and lenses of medium-gray, fine-grained, highly fossiliferous, argillaceous limestone containing nodules, lenses and, locally, irregular beds of dark-gray chert. Lower contact abrupt and placed at top of calcareous quartz sandstone. Total thickness is approximately 23 m (75 ft).
Oriskany Group, undivided (Lower Devonian)
Oriskany Group, undivided (Willard, 1938) - Thickness ranges from 38 m (125 ft) in southwest to 52 m (170 ft) in northeast. Ridgely Sandstone (Swartz and others, 1913) - White-weathering, medium-gray, medium- to thick-bedded, carbonate-cemented quartz-pebble conglomerate and coarse quartz sandstone, which contain abundant brachiopods. Moderately well sorted, subrounded sand gains. Unit thins northeastward and pinches out at Peters Valley. Lower contact abrupt. Thickness ranges from 0 to 10 m (0-32 ft). Shriver Chert (Swartz and others, 1913) - Medium- to dark-gray-weathering, black to dark-gray, medium-to-thick-bedded siltstone and shale containing interbedded black chert and local chert-bearing limestone. Present only in southwestern part of outcrop area where lower contact is gradational with silty limestone of Glenarie Formation. Thickness ranges from 0 to 9 m (0-30 ft). Glenarie Formation (Chadwick, 1908) - Medium-gray-weathering, medium- to dark-gray, fine-grained, thin- to medium-bedded, fossiliferous, silty limestone, and local chert lenses. Unit thickens to northeast. Lower contact probably gradational. Thickness ranges from 17 to 52 m (55-170 ft).
Schoharie Formation (Lower Devonian)
Schoharie Formation (Vanuxem, 1840) - Yellowish-gray- to locally pale-olive-weathering, medium- to dark-gray, medium- to thick-bedded, calcaeous siltstone and lesser amounts of silty limestone. Locally contains thin ribs or pods of black chert in limestone. Limestone content decreases in lower part of unit. Contains the trace fossil Taonurus, a grazing trail. Lower contact gradational and placed at top of highest massive siltstone below lowest limestone. Thickness approximately 53 m (175 ft).
Skunnemunk Conglomerate (Middle Devonian)
Skunnemunk Conglomerate (Darton, 1894) - Grayish-purple to grayish-red, thin- to very thick bedded, locally cross-bedded, polymictic conglomerate and sandstone containing clasts of white vein quartz, red and green quartzite and sandstone, red and gray chert, and red shale; interbedded with medium-gray, thin-bedded sandstone and greenish-gray and grayish-red, mud-cracked shale. Conglomerate and sandstone matrix is primarily hematite and microcrystalline quartz. Conglomerate cobbles range to 16.5 cm (6.5 in) long, and average cobble size increases in upper part of unit. Lower contact conformable and gradational as defined by Kummel and Weller (1902). About 915 m (3,000 ft) thick.
Wantage Sequence (Middle Ordovician)
Wantage Sequence (Monteverde and Herman, 1989) - Restricted, discontinuous sequence of interbedded limestone, dolomite, conglomerate, siltstone, and shale. Upper part is medium-yellowish-brown- to olive-gray-weathering, medium- to dark-gray, very fine to fine-grained, laminated to massive limestone and dolomite that grade down into underlying clastic rocks of lower part. Upper part locally absent. Lower part ranges from grayish-red, medium-gray, pale-brown, and greenish-gray to pale-green mudstone and siltstone containing disseminated subangular to subrounded chert-gravel, quartz-sand lenses, and chert-pebble conglomerate. Lower contact unconformable. Thickness ranges from 0 to 46 m (0-150 ft).